Those versed in the art will recognize a forage harvester or the like as an agricultural machine that harvests field-borne crops and feeds such crops to a rotary cutterhead for reduction into small fragments and for ultimate delivery to a trailing wagon or other receptacle. A typical cutterhead will include a cylindrical member having at its outer surface a plurality of knife supports extending lengthwise of the surface as respects the axis of rotation, and each knife support will carry a cutter knife having a flat portion resting on and affixed to its support and a leading portion extending forwardly of the support, the leading portion being ground to a leading cutting edge which cooperates with a fixed, transverse cutter bar or knife so that crops fed to the cutterhead are reduced as the knives successively pass the fixed knife during high speed rotation of the cutterhead.
The knives are conventionally mounted on their respective supports by bolts or cap screws so that the knives may be readily adjusted relative to the fixed knife and also so that the knives may be removed, in some instances, for sharpening or replacement. The bolt heads project radially outwardly, requiring that the support and knife assemblies be so designed that the bolt heads do not strike the fixed knife and further so that the bolt heads do not suffer premature wear from constant contact with in-fed crops.
A problem which has been incurred in the use of forage harvesters with such cutterheads is non-uniformity of cut. For example, the optimum particle size for crop material chopped with a commercially available forage harvester using a cutterhead as shown in U.S. Pat. No. 4,061,284 is between 0.25 and 0.5 inches. It has been found that crop material pieces up to 3 inches in size are passed through the machine. This problem is particularly acute in corn silage where pieces of corncob and husks are found up to such lengths. Pieces of such lengths are undesirable for two reasons. One is that in most instances the such pieces are not eaten by cattle and thus are wasted. The second reason is that when the processed crop material is ensiled, the longer pieces tend to bridge across other pieces and form air pockets. The formation of air pockets in the ensilage causes oxidation of the crop material and, thus, deterioration of its food value for cattle.